This invention relates to trailer hitches and more particularly to a fifth wheel trailer hitch.
Fifth wheel trailer hitches have long been used to tow a fifth wheel trailer. Fifth wheel hitches have been mounted within the cargo area of pick-up trucks. Commonly, the fifth wheel trailer hitch has a skid plate with a slot therein. The slot is open at its rear end to receive a kingpin extending downward from a trailer pin box. A lock mechanism is located under the skid plate and a commonly uses a jaw like device and is located under the skid plate and secures the kingpin in the skid plate slot. The lock mechanism commonly uses a jaw like device and is often controlled by a handle that extends from the side of the hitch box under the skid plate that can be reached from outside of the cargo area.
The fifth wheel hitch is mounted on a truck. In order to mount the trailer, the truck backs up under the trailer such that the kingpin slides laterally into the slot. However, if the trailer is not level, it is often difficult to determine if the kingpin and skid plate are adequately aligned because of the different cants of the kingpin and skid plate. Furthermore, the tilting of the kingpin with respect to the skid plate can cause a rough engagement which may even cause uncomfortable tilting to the truck.
A fifth wheel hitch that tilts its skid plate to accommodate a smooth engagement between the truck and the trailer has been developed. Some skid plates do not have a mechanism to affix the skid plate after engagement has been made. Affixation of the skid plate with respect to the rest of the housing and the truck may be desirable during towing to reduce side to side rocking of the trailer pin box on the fifth wheel hitch. Other skid plates do have the option to be positively locked out to prevent further side to side rocking motion. However, the anti-rock lockout mechanisms devised to achieve these purposes have been relatively complex and add to the expense of the fifth wheel hitch. Furthermore, these anti-rock lockout mechanisms are controlled by an inconveniently positioned lever which must be actuated from within the cargo area.
What is needed is a fifth wheel that has a tiltable skid plate that provides a smooth and even engagement of the fifth wheel hitch with the kingpin on the trailer and provides full bearing surface support for the kingpin box. What is further needed is an anti-rock lockout mechanism that may be conveniently selected to automatically engage when the skid plate becomes level. What is further needed is a fifth wheel hitch that can accommodate the tilting skid plate and automatic anti-rock locking mechanism in an expeditiously manufactured construction.
In accordance with one aspect of the invention, a fifth wheel trailer hitch includes a housing affixably mountable on a truck. The housing has a rearward facing slot. A skid plate is pivotably mounted on the housing and also has a rearward facing longitudinal slot aligned with the slot in the housing for receiving a kingpin of a trailer. The pivotable motion of the skid plate relative to the housing is a transverse pivotable motion for alignment with a trailer kingpin that is canted with respect to the housing. A locking jaw device secures the kingpin in the slot by engagement about a reduced collar section of the kingpin. The locking jaw device is operably connected to a manually operable handle extending from a side of the housing for opening and closing the hitch about the kingpin. Preferably, the locking jaw device is laterally slidable in the housing to move the locking jaw device between the open position misaligned from the slot and the closed position traversing across the slot.
The manually operable handle is spring biased to the closed position and with a hold for holding said handle in the open position. The hold is preferably in the form of a groove on the handle that abuts an edge of an opening functioning as a detent in the housing through which the handle extends from the housing. The detent is disengaged by the abutment of the kingpin to allow the jaw device to biasly move to the closed position automatically upon entry of the kingpin in the slot. The spring is preferably a compression coil spring coaxially mounted about the handle between a housing sidewall and the locking jaw device.
A lockout device is mounted to the housing and is selectively biased for movement in a direction to automatically engage the skid plate when said skid plate is in a level horizontal position. The lockout device affixes the skid plate in the horizontal level position with respect to the housing and prevents further transverse pivotable motion of the skid plate relative to the housing until the hitch is manually reset. The lockout device is selectively set by the same handle that extends laterally out from said housing.
Preferably, the lockout device includes a lock block affixed onto the handle. The block is biased to move in a direction substantially traverse to the traverse tilting motion of the skid plate. Preferably, the aligned opening is the slot in the skid plate that also receives the kingpin. The block moves into the slot to abut opposing side edges of the slot for locking the skid plate in a horizontal position with respect to the housing. It is desirable that the block is eccentrically mounted about a pivot axis and pivotable into the slot. The handle has a crank section that provides a torque force exerted by gravity to pivot the block into the slot of the skid plate when the slot is aligned with the block.
In accordance with another aspect of the invention, a fifth wheel trailer hitch has a housing that is affixably mountable on a truck having a rearward facing slot. A skid plate is mounted on the housing and has a rearward facing longitudinal slot aligned with the slot in the housing for receiving a kingpin of a trailer. The skid plate is pivotably mounted on the housing for traverse pivotable motion relative to the housing for alignment with a trailer kingpin that is canted with respect to the housing. The locking jaw device secures the kingpin in the slot. The locking jaw device is operably connected to a manually operable handle extending from the housing for opening and closing the hitch about the kingpin. A lockout device is mounted to the housing and is selectively biased for movement in a direction to automatically engage the skid plate when the skid plate is in a level horizontal position. The lockout device affixes the skid plate in the horizontal level position with respect to the housing and prevents further transverse pivotable motion of the skid plate relative to the housing until the hitch is manually reset. The lockout device is biased to move in a direction substantially traverse to the traverse tilting motion of the skid plate.
In accordance with another aspect of the invention, a fifth wheel trailer hitch has its handle operably connected to the locking jaw device to slide it between the open position misaligned from the slot and the closed position where it traverses across the slot. The manually operable handle is spring biased to the closed position. A groove in the handle can engage with a wall edge about an opening in the housing from which the handle extends to form a detent for holding the handle in the open position. The jaw device extends into the slot to be knocked by the kingpin when it enters the slot to disengage the groove from the wall edge to allow the spring bias to move the jaw device to the closed position. As the kingpin moves by the jaw device into the slot, the jaw device moves behind the kingpin across the slot and locks the kingpin in the slot.
In this fashion, a tiltable skid plate has an expeditiously constructed lock-out device that is conveniently reached from outside the cargo area of a pickup truck to optionally and automatically lock out further side-to-side rocking of the skid plate after the trailer and hitch have been coupled together. Furthermore, the jaw device has an easily manufactured hold open device that still allows automatic closing of the hitch to the kingpin.